Soft error rates in integrated circuits are caused by ionizing radiation, such as alpha particles passing through the semiconductor materials of the integrated circuit. Both logic and memory circuits may be effected. The errors are called “soft” because they generally only persist until the next cycle of the integrated circuit function. As an alpha particle passes through semiconductor material a “cloud” of hole-electron pairs are generated in the vicinity of its path. Electric fields present in the integrated circuit can cause the holes and electrons to migrate in opposite directions thus causing extra charge to reach particular circuit nodes and upset the function of the integrated circuit.
As integrated circuit devices continue to be scaled; capacitor cell sizes and operating voltages continue to decrease while circuit density increases. This causes an increase in the probability of an integrated circuit experiencing a soft error. Therefore, there is a need for improved methods and structures for reducing soft error rates in integrated circuits.